CRI听力:Polar bears starve as Arctic sea ice melts

A new study has found that the Arctic's iconic polar bears are finding it harder to hunt for food due to melting sea ice caused by climate change, putting the species at a growing risk of extinction.

Researchers from the United States Geological Survey used high-tech collars to track nine female polar bears for periods of 10 days over three consecutive years.

The study found that polar bears have higher metabolism than previously thought.

About half of the bears under observation lost ten percent or more of their body weight.

"They have to capture at least one seal every five to 10 days, that's just to break even. And if they don't do that they are going to lose weight and if they lose weight then there are other things that come into play with their health, their ability to reproduce and so forth," said George Durner, a co-author of the new study.

The Arctic predator needs sea ice to move around and find spots where they can catch prey.

But because of climate change, sea ice in the region is melting at a rate of 14 per cent per decade, which forces the bears to travel further and use more energy for their hunts.

"If we cut that period short, say the sea ice melt occurs earlier in the summer, then we are essentially pulling the rug out from underneath the polar bears and they don't have that platform any longer to capture seals," said Durner.

According to the National Snow & Ice Data Center, Arctic sea ice in December last year was at its second-lowest level since 1979.

If this trend continues, it could mean smaller bears and fewer cubs for a species that is already endangered.

"Things are likely to get worse before they're going to get better and if it's bad for polar bears it might be affecting us in other ways, us being humans in other ways," said Durner.

The population of polar bears is currently sitting at around 20-thousand.

Researchers estimate that the figure has declined by 40 percent over the past decade.